sources of radiation

radiation sources by umar tauqir

1. RADIATION SOURCES
DR. UMAR TAUQIR
PGR RADIOLOGY
ALNOOR DIAGNOSTICS

3. Introduction
•Scientists have studied radiation for over 100
years and we know a great deal about it.
•Radiation is part of nature. All living creatures,
from the beginning of time, have been, and are still
being, exposed to radiation.
We Live (And Have Always Lived) and we We Live (And Have Always Lived) and we
will live in awill live in a
““Sea of Radiation”Sea of Radiation”

4. Types of Radiation

6. Absorbed Dose
Depends on:
• Whether material is inside or outside
body
• How long material remains in the body
• How much radioactive material there is
• The type of radiation it emits
• What its half-life is

7. Natural and Man-Made
Radiation Sources

8. Natural Background Radiation
•Cosmic Radiation
•Terrestrial Radiation
•Internal Radiation

10. Cosmic Radiation
•The earth, and all living things on it, are
constantly being bombarded by radiation
from outer space (~ 80% protons and 10%
alpha particles).
•Charged particles from the sun and stars
interact with the earth’s atmosphere and
magnetic field to produce a shower of
radiation.
•The amount of cosmic radiation varies in
different parts of the world due to
differences in elevation and to the
effects of the earth’s magnetic field.

12. Terrestrial Radiation
(Uranium, Actinium, Thorium decay series)
•Radioactive material is found throughout
nature in soil, water, and vegetation.
•Important radioactive elements include
uranium and thorium and their radioactive
decay products which have been present
since the earth was formed billions of years
ago.
•Some radioactive material is ingested with
food and water. Radon gas, a radioactive
decay product of uranium is inhaled.
•The amount of terrestrial radiation varies in
different parts of the world due to different
concentrations of uranium and thorium in soil.

14. Internal Radiation
•People are exposed to radiation from radioactive
material inside their bodies. Besides radon, the most
important internal radioactive element is naturally
occurring K-40, but uranium and thorium are also
present as well as H-3 and C-14.
•The amount of radiation from potassium-40 does not
vary much from one person to another. However,
exposure from radon varies significantly from place to
place depending on the amount of uranium in the soil.
•On average, in the United States radon contributes
55% or all radiation exposure from natural and man-
made sources. Another 11% comes from the other
radioactive materials inside the body.

15. Enhanced Natural Sources
•Air travel (cosmic rad. is increased)
•Accumulation of rad. material
(uranium)
•Consumer products (radium dials,
smoke detectors)

16. Locations of Operating Nuclear
Reactors

17. MAN MADE RADIATIONS

21. What is LINAC?
•linear accelerator (LINAC) is the
device most commonly used for
external beam radiation treatments
for patients with cancer. The linear
accelerator is used to treat all
parts/organs of the body. It delivers
high-energy x-rays to the region of
the patient's tumor.

23. Radioactive material is used in:
• Medicine - diagnostic (X-ray, CAT)
• Medicine - therapeutic (Co-60, Linac)
• Medical research (radio-pharmaceuticals,
accel.)
• Industry - (X-ray density gauges, well logging)
Man-Made Radiation

24. Radiation in Medicine
•Radiation used in
medicine is the largest
source of man-made
radiation.
•Most exposure is from
diagnostic x-rays.

25. Man-Made Radiation Sources
•Exposure of selected groups of the
public:
–diagnostic radiology (X-rays)
–nuclear medicine
(radiopharmaceuticals)
–radiotherapy (Co-60, Linacs)

26. Average Annual Effective Dose in
US population (1982)
mSv
Natural Background
Radon 2.0
other 1.0
Occupational 0.009
Medical

diagnostic X-rays0.39
nuclear medicine0.14
__________________________________
Total (rounded) 3.6 mSv / year

27. Natural Background
and Radiation Risk
•Use background radiation to
quantify risk to a lay person.
•Background Equivalent Radiation
Time (BERT).
•Regulatory limits based on natural
radiation (1mSv/year for members
of the public).

28. •ALARA??????

29. PRINCIPAL OF ALARA
•ALARA is an acronym for As Low As
Reasonably Achievable. This is a
radiation safety principle for
minimizing radiation doses and
releases of radioactive materials by
employing all reasonable methods.
ALARA is not only a sound safety
principle, but is a regulatory
requirement for all radiation safety
programs.

30. Radiation Risk
Consent Form:
•5mSv may increase fatal cancer risk by 2
in 10’000 in a lifetime.
•Similar risks are associated with:
- smoking 2 packs of cigarettes in a
lifetime
- driving 2000 miles by car
- living 100 days in New York
N.B.: natural incidence of fatal cancer is about 1 in 3.

31. Examples on Nonionizing
Radiation Sources
•Visible light
•Microwaves
•Radios
•Video Display Terminals
•Power lines
•Radiofrequency
•Lasers

32. Biological Effects
•Lasers (e.g. in patient alignment
equipment)
–Permanent eye injuries
–Cataracts and temporary blinding
–Skin damage

33. Human population in whom
radiation effects have been
observed

34. GOAL
•The ultimate goal is to ultimately
describe the effect of radiation on
humans so that radiation can be used
more safely in diagnosis and more
effectively in therapy